Isocy anato substituted aryl phosphorus esters



United States T" atent Q1 3,013,048 ISOCYANATO SUBSTITUTED ARYLPHOSPHORUS ESTERS Hans Holtschmidt, Koln-Stammheini, Germany, assignorto Farbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany, acorporation of Germany N Drawing. Fiied Jan. 29, 1959, Ser. No. 789,810Claims priority, application Germany Get. 20, 1958 14 Claims. (Cl.260-461) This invention relates to aromatic isocyanates and moreparticularly to isocyanato aromatic esters, thioesters and amidederivatives of phosphoric acid and thiophosphoric acids.

It is an object of this invention to provide isocyanato aromaticphosphoric acid and thiophosphoric acid derivatives. Another object ofthis invention is to provide isocyanato aromatic phosphoric acid andthiophosphoric acid derivatives which may be used to prepare urethaneshaving improved flame resistance. Still another object of this inventionis to provide a process for the preparation of aryl isocyanatophosphoric acid and thiophosphoric acid derivatives.

These objects and others, which will become obvious from the followingdisclosure, are accomplished, in accordance with the invention,generally speaking, by providing isocyanato aryl derivatives ofphosphoric acids. Thus, this invention contemplates isocyanato arylphosphorous esters, thioesters and amides having the formula4,4',4",-triisocyanat0 phenyl phosphate I! -t Q 4,4',4-triisocyanatophenyl thiophosphate 4,4',4"-triisocyanato ben'zyl phosphate4,4',4-triisocyanato benzyl thiophosphate i i 'P-[o-cmQzroo] I i 3Diethy1-4-isocyanatophenyl phosphoric acid triester [HsCzOh-P-OQNCODiethyl-4-isocyanatopheny1 thiophosphonic acid triester [HsCaOlz-P-OONCOCyclopentadieny1-4-isocyanatophenyl phosphoric acid triester, dimethylamide Cyclopentadienyl-4-isocyanatophenyl thiophosphoric acid diesterdimethyl amide Ethyl, vinyl, 4-isocyanato naphthyl phosphoric acid tri-vester 4 NCO Ethyl, vinyl, 4-isocyanato naphthyl thiophosphoric acidtriester NCO' Ethyl phosphoric acid ester-bis (N-methyl-N-4-isocyanato-Ethyl thiopho sphoric acid ester-bis (N-methyl-N-4-isocyanatophenylamide) f (3-isocyanato-5-methyl phenyl) phosphoric acid triester(3-isocyanato-5-methyl phenyl) thiophosphoric. acid triester t rte-$9amide) 4 (3-isocyanato 5 methyl phenyl) dithiophosphoric acid ester,such as, carbomethoxy, carboethoxy and carbotriester. i butoxy, andunsaturated hydrocarbon, such as, vinyl, allyl and butenyl, in additionto the ispcyanato group which is CH3 i NCO attached to a carbon atom ofan aromatic ring. Further, C SP 0G compounds containing more than onephosphoric acid or NCO CH3 7 0 thiophosphoric acid nucleus arecontemplated by the invention. In such cases R and R" may representradicals 4,4',4"-triisocyanatophenyl dithiophosphate of polyhydricalcohols, such as, for example, ethylene glycol, 1,3-propylene glycol,1,4-butylene glycol and the p H 10 like, polyvalent amines, such as, forexample, N,N-di- OCN S [OC NCO] methyl ethylene diamine,N,N-diethyl-1,3-propylene di- 2 amine, N,N-dimethyl-1,3-phenylenediamine, and the like,

linear or branched polyesters, such as, for example, the reactionproduct of succinic acid with trimethylol propane4,4,4"-triisocyanatophenyl tetrath-iophosphate s or ethylene glycol, andthe like, polyethers,,such as, for

1i: 1 example, those obtained from the condensation of alkylene oxidesand compounds such as diethylene glycol, poly- 4-isocyanat0,6-chlorophenyl diethyl phosphoric a id L anudes, polyester amides, suchas, for example, the reaction product of succinic acid with aminoalcohols and more particularly l-amino, Z-hydroxy ethylene and the Cl 0like and polythioethers, such as, for example, thioglycols OCNOO%(OCZH5)Z and more particularly thiodig lycol which link two or morephosphoric acid or thlophosphoric ac1d nuclei through oxygen, sulfurand/or nitrogen atoms. Repre- 4isocyanato, fi-chlorophenyl diethylthiophosphoric acid sentative compounds of this type contemplated by thetriester invention are, for example, those having the followingformulae: Cl s o 0 ester NCO 4,4',4"-triisocyanato benzyldithiophosphate The new isocyanates are prepared by phosgenating thecorresponding amino aryl phosphoric acid derivatives. 7 The amino arylphosphoric acid derivatives may be pre- OCNOCH -SP- 0-0Hz" NOO] pared bynitration followed by reduction or the corre- 2 sponding phosphoric acidand thiophosphoric esters, thiO- 1 esters and amides, such as, forexample, triphenyl phosphate, tricresyl phosphate, triphenylthiophosphate, triphenyl phosphor-amide and the like. Further, the aminoPhenylphosphoric acid ester bis (N,N-4-isocyanato pheny process of thisinvention to prepare the new aromatic iso- O derivatives which arephosgenated in accordance with the C 0i N/ cyauates-may be prepared bythe reaction of phosphoric 1 acid chlorides or substituted phosphoricacid chlorides v 2 with nitrophenols and the like, such as, for example,nitro v henzyl alcohol, nitro naphthol and nitro methylphenol pheny!Phosphor? acid ester bls followed by reduction to the correspondingamines. The methyl Phenyl nude) following examples illustrate thepreparation of reprer 2 V N 0 seutative amino aromatic phosphoric acidand thiophos- I phoric acid derivatives which may be phosgenated inaccordance with the process of the present invention.

NCO About 461 g. (1 mol) of p-nitrophenyl-phosphoric acid-triester,prepared by nitration of triphenyl phosphate in nitric acid (density1.51) at about 5 C, to about (358 0 C. are dissolved in about 3000 cc.of methanol and introduced into a 7-liter stirrer-type autoclave afteradding about 25 g. of fresh Raney nickel. The reduction is completedafter about 2-3 hours at a temperature of about 50 C. and a hydrogenpressure betweenabout 20 p v V l1 and about 40 atm. a Q NO 1 In workingup the product, the reaction mixture is filtered while heating, from thehydrogenation catalyst Phenyl phosphoric acid diester, N,N-4-isocyanatobenzyl amide The substituents in the, above-mentioned formula may andthe filtrate is cooled with ice. About 105 g. of the also containfurther subsutuents, such as, for example, paminophenyl-phosphoricacid-triester are. crystallized halogen, such as chlorine, iodine andbromine; alkoxy, out in the form of small needles. After filtering withsuch as, methoxy, ethoxy and propoxy; carboxylic acid suction, theremainder of the amino-compound is obtained by precipitation with water,whereby about another 210 g. crystallize out, so that the total yield isabout 315 g. (85% of the theoretical). In this way the substance isobtained in an analytically pure form having sharp melting point. It canbe recrystallized from alcohol and is completely soluble in hydrochloricacid and has a melting point of 155 C.

Analysis-Calculated: C, 58.3%; H, 4.86%; N, 11.31%; P, 8.36%. Found: C,58.13%; H, 5.0%; N 11.40%; P, 8.5%.

Example 2 About 195 g. of p-nitrophenyl-thiophosphoric acidtriester,prepared from nitrophenol sodium plus PSCl in xylene (MP. 181 C.183 C.)are dissolved in 1.2 liters of methanol and, after adding about 30 g. ofRaney nickel, are hydrogenated at a temperature of about 50 75 C. and ata hydrogen pressure of about -40 atm. The absorption of hydrogen iscomplete after two hours. After filtering, the main quantity of thep-aminophenylthiophosphoric acid-trimester crystallizes out from themethanol, and the remainder can be obtained by precipitation with Water.Yield: 152 g. (97.5% of the theoretical), M.P. 156 C.

Analysis-Calculated for C H O N PS: C: 56.0%,

H=4.6%, N=10.8%, S== 8.2%, P=8.0%. Found: C=55.6%, H=4.9%, N=10.8%,S=8.2%, P=8.2%. Example3 About 95 g. ofdiethyl-p-nitrophenyl-thiophosphoric acid-triester, dissolved in about300 cc. of methanol, are hydrogenated in the presence of about g. ofRaney nickel at between about 50 and about 60 C. and under a hydrogenpressure of about 20-40 atm. The hydrogen absorption is complete afterthree hours. Thereafter the solid material is filtered oil from thecatalyst and the methanol solution is concentrated. The residue is areddish-yellow oil which is completely soluble in 10% hydrochloric acid.Yield: 86 g.

Analysis. C a l c u l a t e d: N=5.7%, S=13.0%, P=l2.0%. Found: N=5.56%,S=12.0%, P=12.6%.

Analysis of the phenyl urea (M.P. 108 C.): Calculated N=7.7%, S=8.8%,P=8.5%. Found N=7.8%, S=8.3%, P=-8.5.%.

Example 4 About 302 g. of p-nitrophenyl-phosphoric acid-diesterdirnethylamide (prepared from N-dimethylamino-phosphoric acid dichlorideand nitrophenol sodium, M.P. 148 C.) are hydrogenated in about 1.2liters of methanol at about 60 C.75 C. after the addition of about g. ofRaney nickel. The hydrogenation is complete after three hours; the solidmaterial is filtered oil from the catalyst and the filtrate isconcentrated. A light yellow oil which crystallizes on stirring withmethylene chloride is left. Yield: 258 g., \/i.P. 101 C.103 C. (withdecomposition).

Analysis. C al cu l at e d: C=54.6%, H=5.8%, N=13.7%, P=10.1%. Found:C=54.6%, H=5.8%, N=14.2%, P=10.1%.

Example 5 About 268 g. of p-nitrophenyl-phosphoric acid-diester methylphenylamide (prepared according to Example 4) are hydrogenated andworked up as in Example 4. Yield: 220 g., MP. 110 C.-111 C.

Analysis. C a l c 111 ate d: C=61.9%, H=5.4%, N=11.4%, P=8.4%. Found:C=61.9%, H=5.7%, N=11.7%, P=8.5%.

The amino compounds used as starting materials in the process of thisinvention are more particularly disclosed in copending application S.N.790,034.

According to the process of the invention, amino aryl phosphoric acidderivatives or amino aryl thiophosphoric acid derivatives are convertedto the corresponding isocyanates by phosgenation. Any suitablephosgenation method may be used, such as, for example, the coldphase-hot phase phosgenation or even according to the hydrochlorideprocess, the corresponding amine hydrochloride being phosgenated. Asuitable phosgenation process is disclosed in US. Patent 2,680,127. Theprocess can be carried out either continuously or intermittently.Advantageously, one employs an inert solvent, such as, toluene, benzene,xylylene, trichloro ethylene, chlorobenzene, o-dichloro benzene.

The temperature for the phosgenation reaction is not critical. However,it is preferable not to choose too high a temperature for thephosgenation. For this reason, the cold phase-hot phase phosgenation ispreferred to the hydrochloride process. In the cold phase-hot phasephosgenation, the mixture of carbamic acid chloride and aminehydrochloride occurs in such a fine suspension that the hot phasephosgenation is completed in a short time. Temperatures between about C.and about 120 C. are preferred in the final phase of the phosgenation,although higher and lower temperatures may be used, if desired.

Recrystallization or distillation of the isocyanates prepared accordingto the process of this invention is not necessary in most cases, sincethe products are obtained in a relatively pure form. However, anycarbamic acid chloride which may still be present should be destroyed.The excess phosgene may be adequately removed by heating the reactionmixture for a short time at reduced pressure below the boiling point orby blowing an inert gas through the reaction mixture at an elevatedtemperature.

It was not to be expected that the phosgenation of the amino arylphosphoric acid ester derivatives and the like would proceed withoutcleavage of the ester, thioester or amide bonds. However, the process ofthe invention proceeds in a surprisingly simple and convenient manner.The isocyanato aryl phosphoric acid derivatives are obtained inunexpectedly high yields usually exceeding 80% of the theoretical. Theformation of acid chlorides which would be expected from the reaction ofphosgene does not take place. Further, the acid chlorides do not appearas secondary products even in small quantities.

In order to better describe and further classify the invention, thefollowing are specific embodiments.

Example 6 About 1.5 liters of substantially anhydrous 'chlorobenzone areplaced in a three-liter flask, cooled to about 10 C. and thereafterabout 800 g. of phosgene are introduced and condensed. At the sametemperature about 371 g. of finely powdered 4,4,4"-triamino-triphenylphosphate are added in portions. The mixture is stirred for about fourhours in the cold and'then left overnight at room temperature.Thereafter, a powerful stream of phosgene is introduced at a temperatureof between about C. and about C. until a homogeneous solution ispresent. The chlorobenzene solution is then blown out with nitrogen andthe chlorobenzene distilled off in vacuo. The residue isthereaftertreated for approximately another hour at about C. under high vacuum inorder to destroy remaining traces of carbamic acid chloride.

The yellow oil which remains is 4,4',4"-triisocyanato-;

phenyl phosphate. It crystallizes after a few days as ananalytically-pure white .waxy mass. Yield: 380 g. (85% of thetheoretical).

Analysis-Calculated: c, 56.1%; H, 2.68%; N, 9.36%;

P, 6.91%; NCO, 28.1%. Found: C, 55.74%; H, 2.60%; N, 9.70%; P, 6.95%';NCO, 28.3%.

Example 7 chlorobenzene and the mixture is left standing overnight inthe cold. The temperature is thereafter raised with further introductionof phosgene. After about 6 hours, at a phosgenation temperature of about100 C. to about 110 C. everything dissolves except for a slight slimyresidue, which is filtered otf following the addition of substantiallyanhydrous active carbon. A lightyellow melt, 4,4',4"-triisocyanatophenyl thiophosphate, is left, which soon solidifies into crystallineform. Yield 380 g. (82% of the theoretical), M.P. 84 C.86 C.

Analysis.Calculated: C=54.l%, l-I=2.6%, N: 9.05%, P=6.7%, S=6.9%. Found:C=53.9%, H: 2.8%, N=9.1%, P=6.9%, S=7.3%.

Example 8 About 700 g. of phosgene are liquified in about 1.5 liters ofchlorobenzene at about -10 C. Thereafter, a solution of about 475 g. ofdiethyl mono-p-aminophenyl-thiophosphoric acid-triester, dissolved inabout 1 liter of chlorobenzene, is added dropwise so that thetemperature does not rise higher than about C. After standing in thecold overnight, mo-re phosgene is introduced at about 100 C. to about110 C. A light clear solution has formed after about 4 hours. This isworked up as in Example 2. About 472 g. of the slightly brownish oilyisocyanate are obtained as residue. B.P.: 147 C.149 C. (with slightdecomposition).

Analysis-Calculated: N=5.2%, P=l1.4%, 11.8%. Found: N=5.3%, P=ll.0%,S=11.0%.

Example 9 About 220 g. of (p-aminophenyl)-phosphoric-di-estermono-methylphenylarnide are introduced at about 0 C. to a solution of about 500 g.of pliosgene in about 2 liters of chlorobenzene. After standing in thecold overnight, the reaction mixture has solidified to a pasty masswhich becomes liquid again at about 80 C. More phosgene is introducedfor about 4 hours at about 100 to about 110 C. The isocyanate remaining,after distilling off the chlorobenzene, is a light brownish non-.

crystallizing oil. Yield: 220 g.

-Analysis.Calculated: C=59.8%, H=3.8%, N: 10.2%,, P=7.5%. Found:C=59.9%, H=3.8%, N: 10.0%, P=7.4%.

Although only some of the aforementioned. isocyanato aryl phosphoricacid and thiophosphoric acid derivatives were prepared in the foregoingexamples, it is to be understood that any of the class of phosphoricacid derivatives more fully disclosed above can be prepared in a similarmanner. Further, any of the corresponding amino compounds, more fullydisclosed above can be phosgenated in accordance with the processdisclosed by the examples to produce the cor-responding isocyanato arylphosphoric acid derivatives.

It is obvious that the process of the invention may be used to producemonoisocyanates, diisocyanates, triisocyanates or higherpolyisocyanates. The monoisocyanates and polyisocyanates obtainable bythe process of the present invention are useful as starting materialsfor the manufacture of polyurethane plastics. They may be polymerized bythe well-known isocyanate polyaddition process to prepare cellularpolyurethanes or homogeneous polyurethanes having improved flameresistance. Coatings produced from the isocyanates of the presentinvention may be used to replace oil base paint for coating metals orother substrates.

Although the invention has been described in considerable detail in theforegoing for the purpose of illustration, it is to be understood thatsuch detail is solely for this purpose and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention except as is set forth in the claims.

8 What is claimed is: 1. Isocyanato phosphorous compounds having theformula wherein X is selected from the group consisting of oxygen andsulfur, R is selected from the group consisting of O-aryl, O-aralkyl,O-alkaryl, O-cycloalkaryl, S-aryl, S-aralkyl, S-alkaryl, S-cycloalkaryl,N-(aryl) N-(alkyl)(aryl), N-(alkaryl) N(aralkyl) and N(cycloalkaryl) Rand R" are selected from the group consisting of R, O-alkyl,O-cycloalkyl, S-alkyl, S-cycloalkyl, N-(alkyl) and N-(cycloalkyh atleast one of the aryl radicals having at least one isocyanato groupbonded to a carbon atom of the aromatic ring.

2. 4,4,4"-triisocyanato phenyl phosphate.

3. 4,4,4-triisocyanato phenyl thiophosphate.

4. Diethyl mono-p-isocyanato phenyl thiophosphoric acid triester.

5. (p-Isocyanato phenyl)-phosphoric-diester -monomethyl phenyl amide.

6. A process for the preparation of isocyanato phosphorous compoundshaving the formula wherein X is selected from the group consisting ofoxygen and sulfur, R is O-aryl and R and R" are selected from the groupconsisting of R, O-alkyl, O-cycloalkyl, S-allryl, S-cycloalkyl,N-(alkyl) and N-(cyclo-alkyh at least one of the aryl radicals having atleast one isocyanato group bonded to a carbon atom of the aromatic ring.

8. Isocyanato phosphorous compounds having the formula II/ R-P wherein Xis selected from the group consisting of oxygen and sulfur and R isO-aryl, at least one of the aryl radicals having at least one isocyanatogroup bonded to,

'a carbon atom of the aromatic ring.

9'. Isocyanato phosphorous compounds having the formula wherein X isselected from the group consisting of oxygen and sulfur, R and R areO-aryl and R is N-(alkyl)- (aryl), at least one of the aryl radicalshaving at least one isocyanato group bonded to a carbon atom of thearomatic ring.

10. Isocyanato phosphorous compounds having the formula X R M wherein Xis selected from the group consisting of oxygen and sulfur, R is O-aryland R and R" are O-alkyl, said aryl radical having at least oneisocyanato group bonded to a carbon atom of the aromatic ring.

11. A process for the preparation of triisocyanato phen- 1% yl phosphatewhich comprises reacting a triarnino phenyl phosphate with phosgene.

12. A process for the preparation of triisocyanato phenyl thiophosphatewhich comprises reacting a triarnino phenyi thiophos-phate withphosgene.

13. Triisocyanato phenyl phosphates.

14. Tiiisocyanato phenyl thiophosphate.

References Cited in the file of this patent UNITED STATES PATENTS2,691,567 Kvalnes et a1. Oct. 12, 1954

1. ISOCYANATO PHOSPHORUS COMPOUNDS HAVING THE FORMULA
 11. A PROCESS FORTHE PREPARATION OF TRIISOCYANATO PHENPHOPHATE WITH PHOSGENE.